Method of making bars



Sept. 4, 1956 B. BANNISTER 2,761,204

METHOD OF MAKING BARS Filed Feb. 12, 1951 FIEE- FIE-1- [mentors flew/v7"5/4/V/V/57'EE,

United States Patent METHOD OF MAKING BARS Bryant Bannister, Pittsburgh,Pa., assignor to United States Steel Corporation, a corporation of NewJersey Application February 12, 1951, Serial No. 210,585

3 Claims. (Cl. 29-424) This invention relates to a method of making barsand more particularly for making round bars or billets which are to befurther processed into seamless tubes. The conventional method used toproduce these seamless bars or billets is to cast rectangular ingotswhich are rolled into square blooms on a blooming mill. The squareblooms are reduced to a round billet in a bar mill. The rolled bars arecut into the desired lengths, cooled and subjected to a skinning orpeeling operation to remove surface defects. The bars are then reheated,pierced and rolled into seamless tubes in accordance wit-h the usualpractice. This method of making round bars is expensive and in additionthe bars have surface defects caused by rolling rectangular ingots intosquare blooms and then to round bars. A rectangular ingot contains moresurface defects than a cylindrical ingot but it is not economical to usecylindrical ingots in the conventional method because a round section isnot suitable for rolling between cylindrical rolls in a blooming mill.Also in the conventional method a relatively large amount of scrap isproduced because a considerable portion of the ingot containing theshrinkage void is not healed to solid metal and must be cropped off.

It is common practice to cast small ingots, allow them to grow cold,reheat to extrusion temperature, and extrude to the desired form. Thispractice is feasible because in such small castings inherent defects areof a low magnitude and the economics of handling such castings in anyother manner are prohibitive. However, when a plain top ingot ofcommercial size is allowed to cool from a liquid to a low temperature anextensive shrinkage cavity is formed. T'ie magnitude of this cavity orpipe" is a direct function of temperature drop from the liquid state andthe volume of metal undergoing this transition. Hot tops are used tominimize the extent of the shrinkage cavity in the ingot, but this is anadded expense.

it is an object of my invention to provide a method of making barsdirect from a commercial size cast round ingot.

Another object is to provide such a method which pro- .duces a betterbar at less cost.

Still another object is to provide such a method in which a bar is madedirectly from the ingot as cast witlr .out any substantial loss of heat.

A further object is to provide such a method which utilizes a greaterpercentage of the ingot as usable bar.

A still further object is to minimize the phenomena termed segregationwhich is the separation of the low melting point inclusions in thecasting from the base metal. This is accomplished by keeping the voidsin the ingot as small as possible and applying the true compression andmixing effect of extrusion to the ingot.

These and other objects will be more apparent after referring to thefollowing specification and attached drawings, in which:

Figure l is a schematic sectional view showing an ingot in an extrusionpress prior to being extruded; and

2,761,204 Patented Sept. 4, 1956 "ice Figure 2 is a view similar toFigure 1 showing the ingot partly extruded.

In carrying out my method an ingot W, preferably round, of steel orother metal is cast in an ingot mold. As soon as the ingot has been castthe top thereof is sealed by playing a stream of water on the topthereof to form a cap or crust which prevents air from entering as theshrinkage cavity or pipe develops. The ingot is preferably 26 inches indiameter by 6 feet in length and has approximately /8 inch taper perfoot of length. After the top of the ingot is sealed it is strippedwhile very hot and placed in the conventional soaking pit: to equalizethe temperature throughout the ingot. After the temperature has beenequalized the ingot is removed from the soaking pit and thoroughlydescaled, preferably by impinging a jet of high pressure waterprogressively over the entire ingOt surface. The ingot is thenimmediately charged into the cylindrical container 2 of an extrusionpress. The diameter of the container 2 should be slightly larger thanthe largest diameter of the ingot W. Before placing the ingot in thecontainer 2 a plate 4 of glass or glasslike material is placed at thebottom of the container 2 and the ingot may be coated with a similarmaterial. The ingot may be wrapped with spun glass cloth in lieu of orin addition to using the glass plate 4. The use of the glass lubricantwhile not absolutely necessary to my method is very helpful in reducingthe required extrusion pressure, increasing the life of the die, andminimizing surface defects. The ingot is placed in the container 2preferably with the cavity 6 at the top. The ram 8 of the extrusionpress is then moved downwardly compressing the ingot and forcing it outof the forward end of the container through a circular die 10* of thedesired diameter. Since the ingot is subjected to pure compressionduring the extruding action and since the shrinkage cavity is sealedagainst oxidizing gases, the void 6 will be closed during extrusion sothat all but a small butt or slug of the metal of the ingot will beutilized. In this way the yield; that is, the ratio of bar metal toingot metal, is greatly increased over that of the prior practice. Thebar B is preferably round and the reduction ratio is preferablyapproximately 4 to l and should not exceed 60 to l. The productordinarily varies from a minimum of 5 inches in diameter to a maximum of13 inches in diameter. At no time during the above series of operationswill the metal drop below a suitable extrusion temperature. The extrudedsection B is then sawed or sheared from the butt remaining in thecontainer and is preferably surface conditioned by passing itlongitudinally while very hot through a circular oxyacetylene torchwhich burns off a small amount of the surface. After this operation thebar is cut into lengths suitable for the seamless mills.

While one embodiment of my invention has been shown and described, itwill be apparent that other adaptations and modifications may be madewithout departing from the scope of the following claims.

I claim:

1. The method of reducing the amount of scrap in producing ferrous metalbars from a commercial size round ingot which comprises casting a roundingot having a diameter of at least approximately 26 inches and a lengthof at least approximately 6 feet, sealing the top of the ingotimmediately after teeming, equalizing the temperature throughout thecast ingot, descaling the ingot, the foregoing steps being performedwhile maintaining the temperature of the ingot at least at the extensiontemperature, immediately placing the descaled ingot into the containerof an extrusion press with the cavity of the ingot adjacent the entryend of the container, and extruding the ingot into a continuous barwhile using a glass-like luthe container, said extrusion being carriedout by moving a ram against the entry end of the ingot and forcing theferrous metal through the die, the extruding reduction rate beingbetween approximately four to one and sixty to one.

2. The method of reducing the amount of scrap in producing ferrous metalbars according to claim 1 in which a plate of glass-like material isplaced in the die end of the container prior to placing the ingottherein.

3. The method of reducing the amount of scrap in producing ferrous metalbars according to claim 2 in which the hot extruded bar is surfaceconditioned by applying an oxyacetylene flame thereto.

References Cited in the file of this patent UNITED STATES PATENTS811,143 Harrnet Ian. 30, 1906 869,476 Beck Oct. 29, 1907 1,432,803Summey Oct. 24, 1.922 1,646,854 Davis Oct, 25', 1927 4 Singer May 30,Lorant ,Tune 30, Skinner Feb. 8, lones July 26, Anderson Dec. 29,Bucknam July 13, Stem Sept. 19, Lowey Nov. 6, Sejournet Ian. 23,

FOREIGN PATENTS Great Britain July 16, Germany Nov. 3,

OTHER REFERENCES Making and Shaping of Steel, 5th edition, pages 356,

Making, Shaping and Treating of Steel, United States Steel, 5th edition,pages 256, 597, 649, 715 and 716.

1. THE METHOD OF REDUCING THE AMOUNT OF SCRAP IN PRODUCING FERROUS METALBARS FROM A COMMERCIAL SIZE ROUND INGOT WHICH COMPRISES CASTING A ROUNDINGOT HAVING A DIAMETER OF AT LEAST APPROXIMATELY 26 INCHES AND A LENGTHOF AT LEAST APPROXIMATELY 6 FEET, SEALING THE TOP OF THE INGOTIMMEDIATELY AFTER TEEMING, EQUALIZING THE TEMPERATURE THROUGHOUT THECAST INGOT, DESCALING THE INGOT, THE FOREGOING STEPS BEING PERFORMEDWHILE MAINTAINING THE TEMPERATURE OF THE INGOT AT LEAST AT THE EXTENSIONTEMPERATURE, IMMEDIATELY PLACING THE DESCALED INGOT INTO THE CONTAINEROF AN EXTRUSION PRESS WITH THE CAVITY OF THE INGOT ADJACENT THE ENTRYEND OF THE CONTAINER, AND EXTRUDING THE INGOT INTO A CONTINUOUS BARWHILE USING A GLASS-LIKE LUBRICANT AT THE END OF THE INGOT ADJACENT THEDIE END OF THE CONTAINER, SAID EXTRUSION BEING CARRIED OUT BY MOVING ARAM AGAINST THE ENTRY END OF THE INGOT AND FORCING THE FERROUS METALTHROUGH THE DIE, THE EXTRUDING REDUCTION RATE BEING BETWEENAPPROXIMATELY FOUR TO ONE AND SIXTY TO ONE.